First principles study on the structural, electronic, and elastic properties of Na–As systems

We have performed the first principles calculation by using the plane-wave pseudopotential approach with the generalized gradient approximation for investigating the structural, electronic, and elastic properties Na–As systems (NaAs in NaP, LiAs and AuCu-type structures, NaAs2 in MgCu2-type structure, Na3As in Na3As, Cu3P and Li3Bi-type structures, and Na5As4 in A5B4-type structure). The lattice parameters, cohesive energy, formation energy, bulk modulus, and the first derivative of bulk modulus (to fit to Murnaghan’s equation of state) of the related structures are calculated. The second-order elastic constants and the other related quantities such as Young’s modulus, shear modulus, Poisson’s ratio, sound velocities, and Debye temperature are also estimated.